Both Exercise Groups Completed 75 Minutes of Interval Walking Weekly — One in a Single Session, the Other Divided Into Three

Just 75 minutes of brisk interval walking a week — completed in a single session — can reduce belly fat and improve cardiorespiratory fitness in adults with central obesity, a randomized trial from the University of Hong Kong (HKU Med) has found. The benefits proved comparable to those from splitting the same weekly amount across three days, the frequency generally recommended for interval training. Published in Nature Communications, the trial recruited 315 overweight Chinese adults with central obesity in Hong Kong and ran from September 2021 to September 2024. Participants were assigned to one of three groups: once-weekly interval walking, thrice-weekly interval walking, or a control group that attended a 2.5-hour health education session every two weeks.

Both exercise groups completed 75 minutes of interval walking weekly — one in a single session, the other divided into three. Interval training alternates bursts of higher-intensity exercise with lower-intensity recovery, and has been shown to be a time-efficient way to reduce overall and visceral fat. A 'weekend warrior' pattern — compressing most weekly exercise into one or two days — has previously been linked to health benefits, but evidence on whether interval training concentrated into a single weekly session could match a traditional three-day schedule was limited.

Using dual-energy X-ray absorptiometry, the researchers measured body fat at baseline, after 16 weeks, and at 32 weeks. At the 16-week assessment, both interval training groups had significantly reduced total body fat mass, body fat percentage and waist circumference, and had improved their cardiorespiratory fitness compared with the control group. Professor Parco Siu Ming-fai, head of the Division of Kinesiology at HKU Med's School of Public Health and the study's lead author, said the results support once-weekly interval walking as a practical therapeutic option.

'While thrice-weekly interval training remains a commonly recommended approach for the therapeutic management of excess adiposity, our findings show that once-weekly interval training offers similar benefits and represents a practical exercise strategy, he said. 'For many adults with central obesity who struggle to balance work, study, family and other commitments, time constraints are a primary barrier to exercising multiple days per week. Adding a practical takeaway, he said: 'Instead of relying solely on high-frequency exercise prescriptions, once-weekly interval training can be considered a feasible and effective alternative.

Co-first authors are Dr. Leung Chit-kay and Mr. Joshua Bernal, also of the HKU Med School of Public Health. The work was supported by the General Research Fund of the Research Grants Council, the University Grants Committee of Hong Kong, China, and the Seed Fund for Basic Research at HKU. "weekend warrior"